Failures to beacon.min.js

Since the beginning of this month (July 2020) we’ve seen a signficant uptick in the number of failures from the beacon for browser insights.This appears to mostly be IE 11. Has anyone else noticed this? I did see (via doing diffs in the wayback machine) some changes were applied to https://static.cloudflareinsights.com/beacon.min.js around June 23rd.

Uncaught SecurityError: Failed to execute ‘sendBeacon’ on ‘Navigator’: sendBeacon() with a Blob whose type is not any of the CORS-safelisted values for the Content-Type request header is disabled temporarily. See http://crbug.com/490015 for details.

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Same here!

ditto

Received a response from support, I’m including the relevant bit here.


Cloudflare use beacons in order to get the client’s data back to us.
This issue is fixed in Chrome v81: https://bugs.chromium.org/p/chromium/issues/detail?id=724929
We have also added a change to fall back to use ajax instead if the browser does not support sending beacons.